title: Assessment of stability of surface anchors for antibacterial coatings and immobilized growth factors on titanium.
abstract: Titanium (Ti) has been functionalized with biomolecules for biomedical purposes. However, there is very limited information on the stability of such functionalities. Ti surface functionalized with carboxymethyl chitosan (CMCS) and bone morphogenetic protein 2 (BMP-2) has been reported to inhibit bacterial colonization while at the same time enhances osteoblast functions. In this work, three types of anchoring molecules, (3-aminopropyl) triethoxysilane (Silane), dopamine (DA), and polydopamine (PDA), were used for immobilizing the CMCS on Ti. The CMCS-modified surfaces were subjected to 70% ethanol treatment, autoclaving, and prolonged immersion in phosphate buffered saline (PBS). After the treatment procedures, the ability of the CMCS-modified substrates to inhibit colonization by Staphylococcus epidermidis (S. epidermidis) was assessed to evaluate the stability of the immobilized CMCS. The bacterial adhesion assays showed that the CMCS-DA- and CMCS-PDA-modified Ti remained stable after 70% ethanol treatment, autoclaving, and prolonged immersion in PBS, whereas the CMCS-Silane-modified Ti was less stable after autoclaving and prolonged immersion in PBS. The CMCS-DA- and CMCS-PDA-modified Ti substrates were functionalized with BMP-2 and used to support osteoblast growth. Evaluation of alkaline phosphatase (ALP) activity and calcium deposition from osteoblasts cultured on these substrates, which have been treated with 70% ethanol, or subjected to autoclaving, and prolonged immersion in PBS indicated that the immobilized BMP-2 on these surfaces retained its bioactivity.
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge, Singapore 117576, Singapore.
authors.forename: Dong
authors.initials: D
authors.lastname: Zheng
authors.forename: Koon Gee
authors.initials: KG
authors.lastname: Neoh
authors.forename: Zhilong
authors.initials: Z
authors.lastname: Shi
authors.forename: En-Tang
authors.initials: ET
authors.lastname: Kang
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001422:Bacterial Adhesion / Q000187:drug effects; D055396:Bone Morphogenetic Protein 2 / Q000378:metabolism*; D002455:Cell Division; D048271:Chitosan / Q000031:analogs & derivatives* / Q000494:pharmacology; D004298:Dopamine / Q000494:pharmacology*; D004355:Drug Stability; D055767:Immobilized Proteins / Q000378:metabolism*; D007211:Indoles / Q000494:pharmacology*; D010006:Osteoblasts / Q000502:physiology; D011108:Polymers / Q000494:pharmacology*; D011437:Propylamines; D012821:Silanes / Q000494:pharmacology*; D013212:Staphylococcus epidermidis / Q000254:growth & development; D014025:Titanium / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D055396:Bone Morphogenetic Protein 2; D055767:Immobilized Proteins; D007211:Indoles; D011108:Polymers; D011437:Propylamines; D012821:Silanes; C514968:carboxymethyl-chitosan; C568283:polydopamine; D048271:Chitosan; D014025:Titanium; D000469:Alkaline Phosphatase; C477625:amino-propyl-triethoxysilane; D004298:Dopamine
keywords: BMP-2; Bacterial colonization; Carboxymethyl chitosan; Functionalization; Stability; Titanium